Soil conditioner

Abstract

A soil conditioner including a lignin-based compound as an active ingredient and capable of efficiently increasing the amount of microorganisms and inorganic components in soil. The soil conditioner includes a lignin sulfonic acid having a phenolic hydroxyl group content of 0.1% to 5.0% by weight, a methoxyl group content of 1.0% to 15.0% by weight, and a sulfone group-derived sulfur atom content of 2.0% by weight or higher. An improved soil composition, including the soil conditioner and soil; a method for preparing improved soil, including adding the soil conditioner to soil; and a plant production method in which a plant is produced with the improved soil composition are also described.

1 . A soil conditioner, comprising:
 a lignin sulfonic acid having a phenolic hydroxyl group content of 0.1% to 5.0% by weight;   a methoxyl group content of 1.0% to 15.0% by weight; and   a sulfone group-derived sulfur atom content of 2.0% by weight or higher.   
     
     
         2 . The soil conditioner according to  claim 1 , wherein the lignin sulfonic acid has at least one of:
 a sulfur atom content of 1.0% by weight or higher,   a sodium atom content of 0.3% by weight or higher, and   a reducing sugar content of 0.1% by weight or higher.   
     
     
         3 . The soil conditioner according to  claim 1 , wherein the lignin sulfonic acid has a carboxyl group content of 0.1 to 4.5 mmol/g. 
     
     
         4 . The soil conditioner according to  claim 1 , wherein a weight average molecular weight (RI) of the lignin sulfonic acid is 3,000 or more. 
     
     
         5 . The soil conditioner according to  claim 1 , wherein the lignin sulfonic acid comprises a substituent derived from (poly)alkylene oxide. 
     
     
         6 . The soil conditioner according to  claim 1 , which is suitable for agricultural soil. 
     
     
         7 . A biostimulant for a soil, comprising:
 a lignin sulfonic acid having a phenolic hydroxyl group content of 0.1% to 5.0% by weight;   a methoxyl group content of 1.0% to 15.0% by weight; and   a sulfone group-derived sulfur atom content of 2.0% by weight or higher.   
     
     
         8 . An improved soil composition, comprising:
 the soil conditioner according to  claim 1 ; and   soil.   
     
     
         9 . A method for preparing improved soil, the method comprising:
 adding the soil conditioner of  claim 1  to the soil.   
     
     
         10 . A plant production method, comprising:
 producing a plant with the improved soil composition of claim  8 .   
     
     
         11 . An improved soil composition, comprising:
 the biostimulant according to claim  7 ; and   soil.   
     
     
         12 . A method for preparing improved soil, the method comprising:
 adding the biostimulant of claim  7  to the soil.